1. Field
The disclosure relates to circuit design, and in particular, to techniques for decimating periodic signals such as local oscillator signals.
2. Background
Modern communications devices are often required to process two or more signals having different carrier frequencies. For example, a communications transceiver may simultaneously transmit TX signals on one or more TX carrier frequencies, and receive RX signals on one or more RX carrier frequencies. The TX and RX frequency bands may be separated from each other by a duplex offset frequency.
To accommodate the multiple carrier frequencies, a single communications device may employ multiple phase-locked loops (PLL's) to simultaneously generate the desired frequencies. However, multiple PLL's may consume considerable die area on an integrated circuit, leading to higher cost.
It would be desirable to provide techniques for generating multiple carrier frequencies from a single PLL output by, e.g., decimating the signal generated by the PLL, and mixing the component signals to produce the desired carrier frequencies. It would be further desirable to generally apply such techniques to decimating an arbitrary periodic signal to generate another periodic signal of lower frequency.